Breast Cancer Gene Therapy: Development of Novel Non-Invasive Magnetic Resonance Assay to Optimize Efficacy

Gene therapy holds great promise for treatment of breast cancer. In particular clinical trials are underway to apply therapeutic genes related to pro-drug activation or to modulate the activity of oncogenes by blocking promoter sites. However, there are major problems in terms of assessing the delivery to target tissue, assessing the uniformity versus heterogeneity of biodistribution and determining whether the genes are expressed. We propose to design, evaluate and apply a novel approach to gene activity detection- specifically, using fluorinated substrates of -galactosidase to reveal gene activity. Our prototype molecule PFONPG para- fluoro- ortho- nitro- phenyl -Dgalactopyranoside is a direct analog of the traditional yellow biochemical indicator ONPG ortho- nitro- phenyl -Dgalactopyranoside. This shows useful MR characteristics, sensitivity to enzyme activity and ability to enter cells. We will synthesize analogs of this prototype to optimize MR and biological characteristics and explore the feasibility of tailoring the reporter to specific applications, e.g., exploiting -gal activity to deliver specific physiological reporter molecules such as pH and potentially specific cytotoxic agents. The agents will be rigorously tested in solution, applied to cultured breast cancer cells and ultimately used to examine -gal activity in vivo in transfected breast tumors in mice and rats.